1. Field of the Invention
The present invention relates to a seat tube of a bicycle and, more particularly, to a hidden adjustable seat tube device for a bicycle that partially hides a transmission cable inside a seat tube to organize the transmission cable easily, to eliminate multiple redundant segments of the transmission cable, and to mount the transmission cable in the bicycle neatly.
2. Description of the Related Art
A bicycle is a green transportation device that is easy to operate. The bicycle is powered and operated by a user's physical effort without a supply of petroleum that is environmentally hazardous. Thus, transportation through bicycles makes users excise, reduces carbon emissions, and saves energy.
An adjustment of the seat tube height and an operation of brakes of a conventional bicycle are achieved through transmission cables. A controller that connects the transmission cables is mounted in a handlebar, which allows a user to drive the transmission cables easily. When the bicycle is decelerated, the user grips brake-levers that are mounted in the handlebar to drive brakes by one of the transmission cables. When the seat tube height of the bicycle is adjusted, the user operates the controller to drive the other transmission cable that controls a retractable element. The retractable element extents or retracts to abut the seat tube, which adjusts the seat tube height of the bicycle.
However, the multiple transmission cables are mounted in a frame of the bicycle, and the transmission cables are exposed outside the frame. The transmission cables are disarrayed, and the user cannot easily organize the transmission cables. Besides, the transmission cable has multiple redundant segments in turning points of its arrangement, which can prevent the transmission cable from inactively driving the retractable element or the brake. Thus, the redundant segments make the transmission cables chaotically mounted in the frame.